#all{
	width: 1200px;
	background-color: pink;
	margin: 0 auto;
}

#header{
	background-color: aqua;
}
#nav{
	height: 100px;
	background-color: yellow;
}
#content,#content2,#aside{
	width: 400px;
	height: 600px;
}
#content{
	background-color: azure;
	float: left;
}
#content2{
	background-color: beige;
	float: left;
	box-sizing: border-box;
	border: 3px solid red;
	padding: 10px;
}
#aside{
	background-color: bisque;
	float: left;
}
#header,#footer{
	height: 200px;
}
#footer{
	background-color: chartreuse;
	clear: both;
}